Neurological stimulators have been developed to treat pain, movement disorders, functional disorders, spasticity, cancer, cardiac disorders, and various other medical conditions. Implantable neurological stimulation systems generally have an implantable signal generator and one or more leads that deliver electrical pulses to neurological or muscle tissue. For example, several neurological stimulation systems have cylindrical leads that include a lead body with a circular cross-sectional shape and one or more conductive rings (i.e., contacts) spaced apart from each other at the distal end of the lead body. The conductive rings operate as individual electrodes and, in many cases, the leads are implanted percutaneously through a large needle inserted into the epidural space, with or without the assistance of a stylet.
Once implanted, the signal generator applies electrical pulses to the electrodes, which in turn modify the function of the patient's nervous system, such as by altering the patient's responsiveness to sensory stimuli and/or altering the patient's motor-circuit output. In pain treatment, the signal generator applies electrical pulses to the electrodes, which in turn can mask or otherwise alter the patient's sensation of pain.
It is important to accurately position and anchor the leads in order to provide effective therapy. For example, in both traditional low frequency spinal cord stimulation (SCS) and high frequency spinal cord modulation therapy, one or more leads are positioned along a patient's spine to provide therapy to a specific vertebral area. Existing lead anchors can negatively impact lead performance and/or reliability when they allow the lead body to slide or otherwise change position relative to a treatment area. The movement of the lead body relative to the lead anchor can reduce the accuracy with which the stimulation is provided, thus limiting the effectiveness of the therapy. In some cases, the leads must be securely fixed but still be repositionable if a practitioner determines that a different position would provide more effective therapy. As a result, there exists a need for a lead retention mechanism, such as a lead anchor, that mitigates lead movement while providing the ability to subsequently reposition the lead.